I guess that the very first timber stair was a log that was leaned up against something at a higher level, and early man walked up it instead of climbing using his hands. It wouldn't have been long before notches were cut into the log to make steps.

Staircase is not only a great housing decoration but also a long-term investment. Technically, staircase is a number of steps that lead from one level to another. So what are the types of stairs and what kind of stairs’ materials could be used to emphasize the unique style of interior?

There is no reason why the average do it yourself person can't build good looking and functional stairs. Whether it is an internal staircase or just a short few steps up onto an outside deck. The basics are the same.